SwitchTrigger triggers one of the output triggers based on the value of the input port.By Using the Incrementor op we cycle between a number in the range [0..3], which then either draws a sphere, cube, torus or cylinder.

Click anywhere in the patch area and press "f" to turn on the flow-mode (you can also press "cmd + p" and enter "flow"). Now click in the renderer window and click several times. You will see how the flow of the yellow trigger cables changes.